当我尝试创建一个宽正则表达式时，Clang打印出一个奇怪的错误（std :: wregex）
#include <regex>
#include <string>
int main() {
std::wregex myRegex( L"Hello Regex" );
return 0;
}
此代码使用g ++（--std = c ++ 11-Wall）编译时没有任何错误或警告，但是clang ++（ - std = c ++ 11）会生成此错误：
In file included from test.cpp:1:
In file included from /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/regex:60:
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:20: error: non-type template argument is not a constant expression
std::bitset<1 << (8 * sizeof(_CharT))>,
^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:398:53: note: in instantiation of template class
'std::__detail::_BracketMatcher<std::regex_traits<wchar_t>, false, false>' requested here
_BracketMatcher<_TraitsT, __icase, __collate> __matcher
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:316:25: note: in instantiation of function template specialization
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_insert_character_class_matcher<false, false>' requested here
__INSERT_REGEX_MATCHER(_M_insert_character_class_matcher);
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:288:8: note: expanded from macro '__INSERT_REGEX_MATCHER'
__func<false, false>(args);\
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:136:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_atom' requested here
if (this->_M_atom())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:118:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_term' requested here
if (this->_M_term())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:97:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_alternative' requested here
this->_M_alternative();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:82:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_disjunction' requested here
this->_M_disjunction();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:155:14: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_Compiler' requested here
return _Cmplr(__first, __last, __traits, __flags)._M_get_nfa();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:532:27: note: in instantiation of function template specialization
'std::__detail::__compile_nfa<std::regex_traits<wchar_t> >' requested here
_M_automaton(__detail::__compile_nfa(_M_original_str.c_str(),
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:452:9: note: in instantiation of function template specialization 'std::basic_regex<wchar_t,
std::regex_traits<wchar_t> >::basic_regex<const wchar_t *>' requested here
: basic_regex(__p, __p + _Rx_traits::length(__p), __f)
^
test.cpp:5:17: note: in instantiation of member function 'std::basic_regex<wchar_t, std::regex_traits<wchar_t> >::basic_regex' requested here
std::wregex myRegex( L"Hello Regex" );
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:22: note: shift count 32 >= width of type 'int' (32 bits)
std::bitset<1 << (8 * sizeof(_CharT))>,
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:20: error: non-type template argument is not a constant expression
std::bitset<1 << (8 * sizeof(_CharT))>,
^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:398:53: note: in instantiation of template class
'std::__detail::_BracketMatcher<std::regex_traits<wchar_t>, false, true>' requested here
_BracketMatcher<_TraitsT, __icase, __collate> __matcher
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:316:25: note: in instantiation of function template specialization
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_insert_character_class_matcher<false, true>' requested here
__INSERT_REGEX_MATCHER(_M_insert_character_class_matcher);
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:290:8: note: expanded from macro '__INSERT_REGEX_MATCHER'
__func<false, true>(args);\
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:136:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_atom' requested here
if (this->_M_atom())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:118:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_term' requested here
if (this->_M_term())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:97:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_alternative' requested here
this->_M_alternative();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:82:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_disjunction' requested here
this->_M_disjunction();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:155:14: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_Compiler' requested here
return _Cmplr(__first, __last, __traits, __flags)._M_get_nfa();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:532:27: note: in instantiation of function template specialization
'std::__detail::__compile_nfa<std::regex_traits<wchar_t> >' requested here
_M_automaton(__detail::__compile_nfa(_M_original_str.c_str(),
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:452:9: note: in instantiation of function template specialization 'std::basic_regex<wchar_t,
std::regex_traits<wchar_t> >::basic_regex<const wchar_t *>' requested here
: basic_regex(__p, __p + _Rx_traits::length(__p), __f)
^
test.cpp:5:17: note: in instantiation of member function 'std::basic_regex<wchar_t, std::regex_traits<wchar_t> >::basic_regex' requested here
std::wregex myRegex( L"Hello Regex" );
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:22: note: shift count 32 >= width of type 'int' (32 bits)
std::bitset<1 << (8 * sizeof(_CharT))>,
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:20: error: non-type template argument is not a constant expression
std::bitset<1 << (8 * sizeof(_CharT))>,
^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:398:53: note: in instantiation of template class
'std::__detail::_BracketMatcher<std::regex_traits<wchar_t>, true, false>' requested here
_BracketMatcher<_TraitsT, __icase, __collate> __matcher
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:316:25: note: in instantiation of function template specialization
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_insert_character_class_matcher<true, false>' requested here
__INSERT_REGEX_MATCHER(_M_insert_character_class_matcher);
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:293:8: note: expanded from macro '__INSERT_REGEX_MATCHER'
__func<true, false>(args);\
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:136:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_atom' requested here
if (this->_M_atom())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:118:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_term' requested here
if (this->_M_term())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:97:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_alternative' requested here
this->_M_alternative();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:82:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_disjunction' requested here
this->_M_disjunction();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:155:14: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_Compiler' requested here
return _Cmplr(__first, __last, __traits, __flags)._M_get_nfa();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:532:27: note: in instantiation of function template specialization
'std::__detail::__compile_nfa<std::regex_traits<wchar_t> >' requested here
_M_automaton(__detail::__compile_nfa(_M_original_str.c_str(),
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:452:9: note: in instantiation of function template specialization 'std::basic_regex<wchar_t,
std::regex_traits<wchar_t> >::basic_regex<const wchar_t *>' requested here
: basic_regex(__p, __p + _Rx_traits::length(__p), __f)
^
test.cpp:5:17: note: in instantiation of member function 'std::basic_regex<wchar_t, std::regex_traits<wchar_t> >::basic_regex' requested here
std::wregex myRegex( L"Hello Regex" );
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:22: note: shift count 32 >= width of type 'int' (32 bits)
std::bitset<1 << (8 * sizeof(_CharT))>,
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:20: error: non-type template argument is not a constant expression
std::bitset<1 << (8 * sizeof(_CharT))>,
^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:398:53: note: in instantiation of template class
'std::__detail::_BracketMatcher<std::regex_traits<wchar_t>, true, true>' requested here
_BracketMatcher<_TraitsT, __icase, __collate> __matcher
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:316:25: note: in instantiation of function template specialization
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_insert_character_class_matcher<true, true>' requested here
__INSERT_REGEX_MATCHER(_M_insert_character_class_matcher);
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:295:8: note: expanded from macro '__INSERT_REGEX_MATCHER'
__func<true, true>(args);\
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:136:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_atom' requested here
if (this->_M_atom())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:118:17: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_term' requested here
if (this->_M_term())
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:97:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_alternative' requested here
this->_M_alternative();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.tcc:82:13: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_M_disjunction' requested here
this->_M_disjunction();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:155:14: note: in instantiation of member function
'std::__detail::_Compiler<std::regex_traits<wchar_t> >::_Compiler' requested here
return _Cmplr(__first, __last, __traits, __flags)._M_get_nfa();
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:532:27: note: in instantiation of function template specialization
'std::__detail::__compile_nfa<std::regex_traits<wchar_t> >' requested here
_M_automaton(__detail::__compile_nfa(_M_original_str.c_str(),
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex.h:452:9: note: in instantiation of function template specialization 'std::basic_regex<wchar_t,
std::regex_traits<wchar_t> >::basic_regex<const wchar_t *>' requested here
: basic_regex(__p, __p + _Rx_traits::length(__p), __f)
^
test.cpp:5:17: note: in instantiation of member function 'std::basic_regex<wchar_t, std::regex_traits<wchar_t> >::basic_regex' requested here
std::wregex myRegex( L"Hello Regex" );
^
/usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/regex_compiler.h:413:22: note: shift count 32 >= width of type 'int' (32 bits)
std::bitset<1 << (8 * sizeof(_CharT))>,
^
4 errors generated.
GCC版本：4.9.2
锵：
clang version 3.5.0 (tags/RELEASE_350/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
这是一个clang bug还是clang需要一些额外的标题？正常的std :: regex适用于gcc和clang。
答案 0 :(得分：0)
它已经在libstdc ++ trunk中修复，但没有向后移植到4.9。
这是因为1 << (8 * sizeof(_CharT))是1 << 32（_CharT是wchar_t，这里是4字节大）并且它会导致未定义的行为，因为此处1具有类型int并且sizeof(int)是4。